A nickel-iron slag-based shield tunnel wall back-grouting material and its preparation method

Abstract

This invention relates to a nickel-iron slag-based grouting material for the back wall of a shield tunnel. The components, by weight, are as follows: 30-50 parts blast furnace nickel-iron slag, 20-50 parts fly ash, 5-20 parts boron mud, 0.5-3 parts activator, 5-20 parts modifier, 80-110 parts activator solution, 100-150 parts recycled fine aggregate, and 3-5 parts admixture. The water-cement ratio of the nickel-iron slag-based shield tunnel back wall grouting material is 0.45-0.8. Preparation method: Weigh the materials according to the weight percentages; prepare blast furnace nickel-iron slag powder; prepare recycled fine aggregate sand; prepare activator solution; prepare cementitious slurry; add recycled fine aggregate, modifier, and admixture to obtain the nickel-iron slag-based shield tunnel back wall grouting material. This invention is low in energy consumption, energy-saving and environmentally friendly, with low production cost and high production efficiency. It also features high strength, good setting properties and good fluidity. It can replace traditional single-liquid cement grouting materials, effectively reduce the use of silicate cement, and is conducive to the reuse of solid waste resources.

Description

Technical Field

[0001] This invention belongs to the fields of tunnel construction materials and comprehensive utilization of solid waste, and relates to a nickel-iron slag-based shield tunnel wall backfilling material and its preparation method. Background Technology

[0002] With economic and social development, the widespread use of silicate cement as a cementing material in the construction industry has caused serious environmental pollution. During the production process, large amounts of CO2 (accounting for about 5-7% of global carbon emissions), dust, and toxic gases such as sulfur dioxide and nitrogen oxides are emitted, which will exacerbate global warming, cause climate anomalies, and cause serious environmental pollution.

[0003] Traditional single-component grouting materials used in tunnel shield construction suffer from drawbacks such as low early strength, poor stability, susceptibility to segregation and stratification, poor water dispersion resistance, and poor durability. Especially in water-rich geological conditions with high groundwater flow, traditional backfill grouting materials are easily diluted and eroded by groundwater, leading to severe grout stratification and loss, poor hardening effect, low early strength, and difficulty in forming a complete and high-quality relatively impermeable layer, thus failing to achieve the expected backfill grouting effect. Furthermore, the lack of durability means that the grout body easily loses its waterproofing and load-bearing capacity prematurely under the influence of groundwater erosion ions.

[0004] Furthermore, the massive stockpiles of solid waste cannot be naturally degraded through landfill and easily pollute soil and groundwater, posing a pressing problem. Utilizing solid waste to prepare grouting materials for shield tunnel walls, replacing traditional cement-based single-component grouting materials, can effectively reduce CO2 emissions, production costs, and environmental pollution. Moreover, its superior performance, with physical and mechanical properties such as strength and durability exceeding those of ordinary Portland cement, demonstrates broad application prospects. Summary of the Invention

[0005] Purpose of the invention

[0006] This invention proposes a nickel-iron slag-based shield tunnel wall backfilling material and its preparation method to solve the problems of high energy consumption, serious pollution, and poor workability and mechanical properties of existing grouting materials. It has the characteristics of high strength, good fluidity, fast setting time, low bleeding rate, excellent resistance to water corrosion, acid and alkali corrosion, freeze-thaw resistance and carbonization resistance, low cost and convenient and quick construction process. It can solve the problem of energy consumption and reduce CO2 of traditional building materials, and reduce environmental pollution.

[0007] Technical solution

[0008] A nickel-iron slag-based shield tunnel wall backfilling material, by mass parts, comprises the following components: 30-50 parts blast furnace nickel-iron slag, 20-50 parts fly ash, 5-20 parts boron mud, 0.5-3 parts activator, 5-20 parts modifier, 80-110 parts activator solution, 100-150 parts recycled fine aggregate, and 3-5 parts admixture. The water-cement ratio of the nickel-iron slag-based shield tunnel wall backfilling material is 0.45-0.8.

[0009] Furthermore, the blast furnace nickel-iron slag is a solid waste slag produced from the smelting of nickel-iron alloys. Its chemical composition, by weight percentage, is as follows: SiO2: 25-30%, Al2O3: 25-35%, CaO: 20-30%, FeO: 3-5%, MgO: 5-10%. The blast furnace nickel-iron slag is ball-milled and activated using a planetary ball mill with an activator for 60-120 minutes at a speed of 350-450 rpm. The resulting blast furnace nickel-iron slag powder, obtained by passing through a 200-mesh sieve, has a median particle size of 6-10 μm and a specific surface area of ​​500-650 m². 2 / kg.

[0010] Furthermore, the activator is desulfurized gypsum, with the following chemical composition by weight percentage: CaO: 40-50%, SO3: 45-55%, SiO2: 3-5%, and median particle size of 3-5 μm.

[0011] Furthermore, the chemical composition of the fly ash, by weight percentage, is as follows: SiO2: 55-65%, Al2O3: 15-22%, Fe2O3: 5.5-10%, CaO: 3.3-7%, belonging to low-calcium fly ash, with a fineness of over 200 mesh and a specific surface area of ​​600-700 m². 2 / kg.

[0012] Furthermore, the boron mud has the following chemical composition by weight percentage: MgO: 45-55%, Al2O3: 2-5%, SiO2: 22-27%, CaO: 10-13%, Na2O: 1-3%, and passes through a 30-mesh sieve.

[0013] Furthermore, the activator solution is prepared from water glass, solid sodium hydroxide particles, and added water, with the mass ratio of solid sodium hydroxide particles to water glass being 0.1 to 0.25; the water-cement ratio is the mass ratio of added water in the activator solution, water in the water glass, and solid cementing material, and the solid cementing material is high-alumina nickel-iron slag, fly ash, and boron mud.

[0014] Furthermore, the blending agent is coal gangue powder, and its chemical composition by weight percentage is as follows: SiO2: 52-65%, Al2O3: 16-36%, Fe2O3: 2-10%, CaO: 0.4-2.3%, MgO: 0.4-2.4%.

[0015] Furthermore, the recycled fine aggregate is composed of waste concrete. After being crushed, the waste concrete is ball-milled mechanically for 30 to 180 minutes at a speed of 400 to 500 revolutions per minute. The fineness meets the following requirements: 10% to 0% residue on a square-hole sieve with a side length of 4.75 mm, 45% to 25% residue on a 2.36 mm sieve, and 65% to 45% residue on a 1.18 mm sieve.

[0016] Furthermore, the additive is composed of 0.5 to 2 parts by weight of polycarboxylate superplasticizer, 0.5 to 2 parts by weight of hydroxypropyl methylcellulose ether, and 0.5 to 2 parts by weight of redispersible latex powder.

[0017] A method for preparing a nickel-iron slag-based shield tunnel wall backfill grouting material includes the following steps:

[0018] 1) Weigh out 30-50 parts of blast furnace nickel-iron slag, 20-50 parts of fly ash, 5-20 parts of boron mud, 0.5-3 parts of activator, 5-20 parts of blender, 80-110 parts of activator solution, 100-150 parts of recycled fine aggregate, and 3-5 parts of admixture according to the following weight proportions.

[0019] 2) Use a drying oven to dry the blast furnace nickel-iron slag and recycled fine aggregate until the moisture content is no more than 1%. Use a ball mill to mix the activator with the blast furnace nickel-iron slag, grind and sieve to obtain blast furnace nickel-iron slag powder. After crushing, the recycled fine aggregate is ball-milled mechanically. The ground recycled fine aggregate is then sieved to obtain recycled fine aggregate sand, which is medium sand.

[0020] 3) Add solid NaOH granules to the added water while stirring continuously to prevent NaOH from clumping, to obtain a NaOH solution; further mix and stir the water glass with the NaOH solution to obtain an activator solution;

[0021] 4) Add blast furnace nickel-iron slag powder, fly ash, and boron mud to a planetary mixer and mix at a speed of 60-80 r / min for 80-100 s to obtain a mixed powder. Then add an activator solution in the same weight proportion and mix thoroughly at 60-80 r / min for 3-5 min to obtain a cementitious slurry.

[0022] 5) Add recycled fine aggregate, modifier and additive to the cementitious material slurry and stir at a speed of 120-250 r / min for 1-3 min to obtain nickel-iron slag-based shield tunnel wall backfill grouting material.

[0023] Advantages and effects

[0024] 1) This invention uses nickel-iron slag, fly ash, and boron mud as cementing materials to replace cement in the preparation of grouting materials. This not only reduces production costs and environmental pollution and realizes the resource utilization of solid waste, but also improves strength, increases the impermeability and stone-forming rate of grouting materials, and reduces particle separation and water separation characteristics within the grouting materials.

[0025] 2) The synergistic effect of mechanochemical coupling activation is utilized. Through mechanical activation and the action of desulfurized gypsum, the hydration reaction activity of nickel-iron slag can be effectively improved, promoting its glassy depolymerization, generating a large amount of CSH and calcium vanadium, optimizing pores and cracks, and generating a dense microstructure. At the same time, the chemical composition of the raw materials is optimized, and the ratio of Ca / Si and Al is optimized. By incorporating fly ash, boron mud and coal gangue, the structural strength and durability of nickel-iron slag-based grouting materials can be effectively improved, and its setting time and flow properties can be significantly improved, which is convenient for engineering construction.

[0026] 3) Mechanical activation dehydrates and embrittles the cement stone and mortar adhering to the surface of recycled aggregates, improves the quality of recycled aggregates, facilitates the bonding between cementitious materials and aggregates, increases the strength of the interface transition zone, and significantly improves the mechanical properties of grouting materials.

[0027] 4) To address the issue of high bleeding rate in conventional shield tunnel wall grouting materials, coal gangue powder is used as a modifier. Its porous structure effectively reduces the free water content during mixing. Simultaneously, it participates in the hydration reaction, generating a large amount of hydrated calcium silicate and calcium vanadate, increasing structural density and improving mechanical properties. Furthermore, the use of redispersible latex powder and hydroxypropyl methylcellulose ether promotes the overlapping of gel products to form a continuous matrix. This matrix effectively adsorbs onto the pore surface of the grout, blocking pore connectivity and preventing pore aggregation and disproportionation, thereby improving pore stability and effectively reducing bleeding rate. Attached Figure Description

[0028] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. The scope of protection of the present invention is not limited to the following description.

[0029] Figure 1 A schematic diagram of the preparation method for grouting material for the back wall of a nickel-iron slag-based shield tunnel. Detailed Implementation

[0030] A nickel-iron slag-based shield tunnel wall backfilling grouting material: by mass parts, the components are as follows: 30-50 parts blast furnace nickel-iron slag, 20-50 parts fly ash, 5-20 parts boron mud, 0.5-3 parts activator, 5-20 parts modifier, 80-110 parts activator solution, 100-150 parts recycled fine aggregate, 3-5 parts admixture, and the water-cement ratio of the nickel-iron slag-based shield tunnel wall backfilling grouting material is 0.45-0.8.

[0031] Blast furnace nickel-iron slag is a solid waste slag produced during the smelting of nickel-iron alloys. Its chemical composition, by weight percentage, is as follows: SiO2: 25-30%, Al2O3: 25-35%, CaO: 20-30%, FeO: 3-5%, MgO: 5-10%. The blast furnace nickel-iron slag is ball-milled and activated using a planetary ball mill with an activator for 60-120 minutes at a speed of 350-450 rpm. The resulting blast furnace nickel-iron slag powder, obtained by passing through a 200-mesh sieve, has a median particle size of 6-10 μm and a specific surface area of ​​500-650 m². 2 / kg.

[0032] The activator is desulfurized gypsum, and its chemical composition by weight percentage is as follows: CaO: 40-50%, SO3: 45-55%, SiO2: 3-5%, with a median particle size of 3-5 μm.

[0033] The chemical composition of fly ash, by weight percentage, is as follows: SiO2: 55-65%, Al2O3: 15-22%, Fe2O3: 5.5-10%, CaO: 3.3-7%. It belongs to low-calcium fly ash, with a fineness of over 200 mesh and a specific surface area of ​​600-700 m². 2 / kg.

[0034] The chemical composition of the boron mud, by weight percentage, is as follows: MgO: 45-55%, Al2O3: 2-5%, SiO2: 22-27%, CaO: 10-13%, Na2O: 1-3%, passing through a 30-mesh sieve.

[0035] The activator solution is prepared from water glass, solid sodium hydroxide particles, and added water. The mass ratio of solid sodium hydroxide particles to water glass is 0.1–0.25; the water glass modulus (M = moles of SiO2 / moles of Na2O) is 3.3, and the solid content is 35.5% (SiO2). 2: 26.98%, Na2O: 8.53%), Baumé degree 38.5; water-cement ratio is the mass ratio of water added to the activator solution, water in water glass to solid cementitious materials, the solid cementitious materials are high-alumina nickel-iron slag, fly ash and boron mud.

[0036] The blending agent is coal gangue powder, with the following chemical composition by weight percentage: SiO2: 52-65%, Al2O3: 16-36%, Fe2O3: 2-10%, CaO: 0.4-2.3%, MgO: 0.4-2.4%.

[0037] The recycled fine aggregate is composed of waste concrete. After the waste concrete is crushed, it is ball-milled mechanically for 30 to 180 minutes at a speed of 400 to 500 revolutions per minute. The fineness meets the following requirements: 10% to 0% residue on a square hole sieve with a side length of 4.75 mm, 45% to 25% residue on a 2.36 mm sieve, and 65% to 45% residue on a 1.18 mm sieve.

[0038] The additive consists of 0.5 to 2 parts by weight of polycarboxylate superplasticizer, 0.5 to 2 parts by weight of hydroxypropyl methylcellulose ether, and 0.5 to 2 parts by weight of redispersible latex powder.

[0039] like Figure 1 The preparation method flowchart shows a method for preparing a nickel-iron slag-based shield tunnel wall backfill grouting material, which includes the following steps:

[0040] 1) Weigh out 30-50 parts of blast furnace nickel-iron slag, 20-50 parts of fly ash, 5-20 parts of boron mud, 0.5-3 parts of activator, 5-20 parts of blender, 80-110 parts of activator solution, 100-150 parts of recycled fine aggregate, and 3-5 parts of admixture according to the following weight proportions.

[0041] 2) Use an electric heating blast drying oven to dry the blast furnace nickel-iron slag and recycled fine aggregate until the moisture content is no more than 1%. Use a ball mill to mix the activator with the blast furnace nickel-iron slag, grind and sieve to obtain blast furnace nickel-iron slag powder. After crushing, the recycled fine aggregate is ball-milled mechanically. The ground recycled fine aggregate is then sieved to obtain recycled fine aggregate sand as medium sand.

[0042] 3) Add solid NaOH granules to the added water while stirring continuously to prevent NaOH from clumping, to obtain a NaOH solution; further mix and stir the water glass with the NaOH solution to obtain an activator solution;

[0043] 4) Add blast furnace nickel-iron slag powder, fly ash, and boron mud to a planetary mixer and mix at a speed of 60-80 r / min for 80-100 s to obtain a mixed powder. Then add an activator solution in the same weight proportion and mix thoroughly at 60-80 r / min for 3-5 min to obtain a cementitious slurry.

[0044] 5) Add recycled fine aggregate, modifier and additive to the cementitious material slurry and stir at a speed of 120-250 r / min for 1-3 min to obtain nickel-iron slag-based shield tunnel wall backfill grouting material.

[0045] Example 1

[0046] 1) Weigh out 50 parts by weight of blast furnace nickel-iron slag, 20 parts by weight of fly ash, 20 parts by weight of boron mud, 3 parts by weight of activator, 20 parts by weight of blender, 110 parts by weight of activator solution, 150 parts by weight of recycled fine aggregate, and 4.5 parts by weight of admixture (composed of 0.5 parts by weight of polycarboxylate superplasticizer, 2 parts by weight of hydroxypropyl methylcellulose ether, and 2 parts by weight of redispersible latex powder). The water-cement ratio of the nickel-iron slag-based shield tunnel wall backfill grouting material is 0.8.

[0047] 2) Use an electric heating blast drying oven to dry the blast furnace nickel-iron slag and recycled fine aggregate until the moisture content is no more than 1%. Use a ball mill to mix the activator with the blast furnace nickel-iron slag, grind and sieve to obtain blast furnace nickel-iron slag powder. After crushing, the recycled fine aggregate is ball-milled mechanically. The ground recycled fine aggregate is then sieved to obtain recycled fine aggregate sand as medium sand.

[0048] 3) Add solid NaOH granules to the added water while stirring continuously to prevent NaOH from clumping, to obtain a NaOH solution; further mix and stir the water glass with the NaOH solution to obtain an activator solution;

[0049] 4) Add blast furnace nickel-iron slag powder, fly ash, and boron mud to a planetary mixer and mix at a speed of 60-80 r / min for 80-100 s to obtain a mixed powder. Then add an activator solution in the same weight proportion and mix thoroughly at 60-80 r / min for 3-5 min to obtain a cementitious slurry.

[0050] 5) Add recycled fine aggregate, modifier and additive to the cementitious material slurry and stir at a speed of 120-250 r / min for 1-3 min to obtain nickel-iron slag-based shield tunnel wall backfill grouting material.

[0051] Example 2

[0052] 1) Weigh out 45 parts of blast furnace nickel-iron slag, 40 parts of fly ash, 15 parts of boron mud, 2.5 parts of activator, 15 parts of blender, 100 parts of activator solution, 130 parts of recycled fine aggregate, and 5 parts of admixture (composed of 1 part of polycarboxylate superplasticizer, 2 parts of hydroxypropyl methylcellulose ether, and 2 parts of redispersible latex powder by weight). The water-cement ratio of the nickel-iron slag-based shield tunnel wall backfill grouting material is 0.7.

[0053] 2) Use an electric heating blast drying oven to dry the blast furnace nickel-iron slag and recycled fine aggregate until the moisture content is no more than 1%. Use a ball mill to mix the activator with the blast furnace nickel-iron slag, grind and sieve to obtain blast furnace nickel-iron slag powder. After crushing, the recycled fine aggregate is ball-milled mechanically. The ground recycled fine aggregate is then sieved to obtain recycled fine aggregate sand as medium sand.

[0054] 3) Add solid NaOH granules to the added water while stirring continuously to prevent NaOH from clumping, to obtain a NaOH solution; further mix and stir the water glass with the NaOH solution to obtain an activator solution;

[0055] 4) Add blast furnace nickel-iron slag powder, fly ash, and boron mud to a planetary mixer and mix at a speed of 60-80 r / min for 80-100 s to obtain a mixed powder. Then add an activator solution in the same weight proportion and mix thoroughly at 60-80 r / min for 3-5 min to obtain a cementitious slurry.

[0056] 5) Add recycled fine aggregate, modifier and additive to the cementitious material slurry and stir at a speed of 120-250 r / min for 1-3 min to obtain nickel-iron slag-based shield tunnel wall backfill grouting material.

[0057] Example 3

[0058] 1) Weigh out 50 parts by weight of blast furnace nickel-iron slag, 40 parts by weight of fly ash, 5 parts by weight of boron mud, 3 parts by weight of activator, 5 parts by weight of blender, 90 parts by weight of activator solution, 100 parts by weight of recycled fine aggregate, and 5 parts by weight of admixture (2 parts by weight of polycarboxylate superplasticizer, 1 part by weight of hydroxypropyl methylcellulose ether, and 1 part by weight of redispersible latex powder). The water-cement ratio of the nickel-iron slag-based shield tunnel wall backfill grouting material is 0.5.

[0059] 2) Use an electric heating blast drying oven to dry the blast furnace nickel-iron slag and recycled fine aggregate until the moisture content is no more than 1%. Use a ball mill to mix the activator with the blast furnace nickel-iron slag, grind and sieve to obtain blast furnace nickel-iron slag powder. After crushing, the recycled fine aggregate is ball-milled mechanically. The ground recycled fine aggregate is then sieved to obtain recycled fine aggregate sand as medium sand.

[0060] 3) Add solid NaOH granules to the added water while stirring continuously to prevent NaOH from clumping, to obtain a NaOH solution; further mix and stir the water glass with the NaOH solution to obtain an activator solution;

[0061] 4) Add blast furnace nickel-iron slag powder, fly ash, and boron mud to a planetary mixer and mix at a speed of 60-80 r / min for 80-100 s to obtain a mixed powder. Then add an activator solution in the same weight proportion and mix thoroughly at 60-80 r / min for 3-5 min to obtain a cementitious slurry.

[0062] 5) Add recycled fine aggregate, modifier and additive to the cementitious material slurry and stir at a speed of 120-250 r / min for 1-3 min to obtain nickel-iron slag-based shield tunnel wall backfill grouting material.

[0063] Example 4

[0064] 1) Weigh out 30 parts by weight of blast furnace nickel-iron slag, 50 parts by weight of fly ash, 20 parts by weight of boron mud, 0.5 parts by weight of activator, 5 parts by weight of blender, 80 parts by weight of activator solution, 130 parts by weight of recycled fine aggregate, and 3 parts by weight of admixture (composed of 2 parts by weight of polycarboxylate superplasticizer, 0.5 parts by weight of hydroxypropyl methylcellulose ether, and 0.5 parts by weight of redispersible latex powder). The water-cement ratio of the nickel-iron slag-based shield tunnel wall backfill grouting material is 0.45.

[0065] 2) Use an electric heating blast drying oven to dry the blast furnace nickel-iron slag and recycled fine aggregate until the moisture content is no more than 1%. Use a ball mill to mix the activator with the blast furnace nickel-iron slag, grind and sieve to obtain blast furnace nickel-iron slag powder. After crushing, the recycled fine aggregate is ball-milled mechanically. The ground recycled fine aggregate is then sieved to obtain recycled fine aggregate sand as medium sand.

[0066] 3) Add solid NaOH granules to the added water while stirring continuously to prevent NaOH from clumping, to obtain a NaOH solution; further mix and stir the water glass with the NaOH solution to obtain an activator solution;

[0067] 4) Add blast furnace nickel-iron slag powder, fly ash, and boron mud to a planetary mixer and mix at a speed of 60-80 r / min for 80-100 s to obtain a mixed powder. Then add an activator solution in the same weight proportion and mix thoroughly at 60-80 r / min for 3-5 min to obtain a cementitious slurry.

[0068] 5) Add recycled fine aggregate, modifier and additive to the cementitious material slurry and stir at a speed of 120-250 r / min for 1-3 min to obtain nickel-iron slag-based shield tunnel wall backfill grouting material.

[0069] Comparative Example 1

[0070] 1) Weigh out 50 parts by weight of blast furnace nickel-iron slag, 20 parts by weight of fly ash, 0 parts by weight of boron mud, 3 parts by weight of activator, 20 parts by weight of blender, 110 parts by weight of activator solution, 150 parts by weight of recycled fine aggregate, and 4.5 parts by weight of admixture (composed of 0.5 parts by weight of polycarboxylate superplasticizer, 2 parts by weight of hydroxypropyl methylcellulose ether, and 2 parts by weight of redispersible latex powder). The water-cement ratio of the nickel-iron slag-based shield tunnel wall backfill grouting material is 0.8.

[0071] 2) Use an electric heating blast drying oven to dry the blast furnace nickel-iron slag and recycled fine aggregate until the moisture content is no more than 1%. Use a ball mill to mix the activator with the blast furnace nickel-iron slag, grind and sieve to obtain blast furnace nickel-iron slag powder. After crushing, the recycled fine aggregate is ball-milled mechanically. The ground recycled fine aggregate is then sieved to obtain recycled fine aggregate sand as medium sand.

[0072] 3) Add solid NaOH granules to the added water while stirring continuously to prevent NaOH from clumping, to obtain a NaOH solution; further mix and stir the water glass with the NaOH solution to obtain an activator solution;

[0073] 4) Add blast furnace nickel-iron slag powder, fly ash, and boron mud to a planetary mixer and mix at a speed of 60-80 r / min for 80-100 s to obtain a mixed powder. Then add an activator solution in the same weight proportion and mix thoroughly at 60-80 r / min for 3-5 min to obtain a cementitious slurry.

[0074] 5) Add recycled fine aggregate, modifier and additive to the cementitious material slurry and stir at a speed of 120-250 r / min for 1-3 min to obtain nickel-iron slag-based shield tunnel wall backfill grouting material.

[0075] Comparative Example 2

[0076] 1) Weigh out 50 parts by weight of blast furnace nickel-iron slag, 20 parts by weight of fly ash, 20 parts by weight of boron mud, 0 parts by weight of activator, 20 parts by weight of blender, 110 parts by weight of activator solution, 150 parts by weight of recycled fine aggregate, and 4.5 parts by weight of admixture (composed of 0.5 parts by weight of polycarboxylate superplasticizer, 2 parts by weight of hydroxypropyl methylcellulose ether, and 2 parts by weight of redispersible latex powder). The water-cement ratio of the nickel-iron slag-based shield tunnel wall backfill grouting material is 0.8.

[0077] 2) Use an electric heating blast drying oven to dry the blast furnace nickel-iron slag and recycled fine aggregate until the moisture content is no more than 1%. Use a ball mill to mix the activator with the blast furnace nickel-iron slag, grind and sieve to obtain blast furnace nickel-iron slag powder. After crushing, the recycled fine aggregate is ball-milled mechanically. The ground recycled fine aggregate is then sieved to obtain recycled fine aggregate sand as medium sand.

[0078] 3) Add solid NaOH granules to the added water while stirring continuously to prevent NaOH from clumping, to obtain a NaOH solution; further mix and stir the water glass with the NaOH solution to obtain an activator solution;

[0079] 4) Add blast furnace nickel-iron slag powder, fly ash, and boron mud to a planetary mixer and mix at a speed of 60-80 r / min for 80-100 s to obtain a mixed powder. Then add an activator solution in the same weight proportion and mix thoroughly at 60-80 r / min for 3-5 min to obtain a cementitious slurry.

[0080] 5) Add recycled fine aggregate, modifier and additive to the cementitious material slurry and stir at a speed of 120-250 r / min for 1-3 min to obtain nickel-iron slag-based shield tunnel wall backfill grouting material.

[0081] Comparative Example 3

[0082] 1) Weigh out 50 parts of blast furnace nickel-iron slag, 0 parts of fly ash, 20 parts of boron mud, 3 parts of activator, 20 parts of blender, 110 parts of activator solution, 150 parts of recycled fine aggregate, and 4.5 parts of admixture (composed of 0.5 parts of polycarboxylate superplasticizer, 2 parts of hydroxypropyl methylcellulose ether, and 2 parts of redispersible latex powder by weight). The water-cement ratio of the nickel-iron slag-based shield tunnel wall backfill grouting material is 0.8.

[0083] 2) Use an electric heating blast drying oven to dry the blast furnace nickel-iron slag and recycled fine aggregate until the moisture content is no more than 1%. Use a ball mill to mix the activator with the blast furnace nickel-iron slag, grind and sieve to obtain blast furnace nickel-iron slag powder. After crushing, the recycled fine aggregate is ball-milled mechanically. The ground recycled fine aggregate is then sieved to obtain recycled fine aggregate sand as medium sand.

[0084] 3) Add solid NaOH granules to the added water while stirring continuously to prevent NaOH from clumping, to obtain a NaOH solution; further mix and stir the water glass with the NaOH solution to obtain an activator solution;

[0085] 4) Add blast furnace nickel-iron slag powder, fly ash, and boron mud to a planetary mixer and mix at a speed of 60-80 r / min for 80-100 s to obtain a mixed powder. Then add an activator solution in the same weight proportion and mix thoroughly at 60-80 r / min for 3-5 min to obtain a cementitious slurry.

[0086] 5) Add recycled fine aggregate, modifier and additive to the cementitious material slurry and stir at a speed of 120-250 r / min for 1-3 min to obtain nickel-iron slag-based shield tunnel wall backfill grouting material.

[0087] Comparative Example 4

[0088] 1) Weigh out 50 parts by weight of blast furnace nickel-iron slag, 20 parts by weight of fly ash, 20 parts by weight of boron mud, 3 parts by weight of activator, 0 parts by weight of blender, 110 parts by weight of activator solution, 150 parts by weight of recycled fine aggregate, and 4.5 parts by weight of admixture (composed of 0.5 parts by weight of polycarboxylate superplasticizer, 2 parts by weight of hydroxypropyl methylcellulose ether, and 2 parts by weight of redispersible latex powder). The water-cement ratio of the nickel-iron slag-based shield tunnel wall backfill grouting material is 0.8.

[0089] 2) Use an electric heating blast drying oven to dry the blast furnace nickel-iron slag and recycled fine aggregate until the moisture content is no more than 1%. Use a ball mill to mix the activator with the blast furnace nickel-iron slag, grind and sieve to obtain blast furnace nickel-iron slag powder. After crushing, the recycled fine aggregate is ball-milled mechanically. The ground recycled fine aggregate is then sieved to obtain recycled fine aggregate sand as medium sand.

[0090] 3) Add solid NaOH granules to the added water while stirring continuously to prevent NaOH from clumping, to obtain a NaOH solution; further mix and stir the water glass with the NaOH solution to obtain an activator solution;

[0091] 4) Add blast furnace nickel-iron slag powder, fly ash, and boron mud to a planetary mixer and mix at a speed of 60-80 r / min for 80-100 s to obtain a mixed powder. Then add an activator solution in the same weight proportion and mix thoroughly at 60-80 r / min for 3-5 min to obtain a cementitious slurry.

[0092] 5) Add recycled fine aggregate, modifier and additive to the cementitious material slurry and stir at a speed of 120-250 r / min for 1-3 min to obtain nickel-iron slag-based shield tunnel wall backfill grouting material.

[0093] All the above embodiments are prepared using the method provided by the present invention and conform to the standard TCECS 563-2018 "Technical Specification for Application of Synchronous Grouting Materials in Shield Tunneling".

[0094] Table 1. Examples of a nickel-iron slag-based grouting material for shield tunnel walls.

[0095]

[0096] Table 2 Comparative Performance of a Nickel-Iron Slag-Based Backfilling Material for Shield Tunnels

[0097]

[0098] By comparing the data in Tables 1 and 2 with those in Examples 1-4 and Comparative Examples 1-4, it can be seen that, using the same preparation method as this invention, the materials selected in this patent can improve the compressive strength, bleeding rate, fluidity, and other properties of the post-wall grouting material, and the effect is significantly different. Therefore, the technology of this invention has significant effects.

[0099] Compared with existing technologies, the nickel-iron slag-based shield tunnel wall grouting material and its preparation method provided by this invention are low in energy consumption, energy-saving and environmentally friendly, low in production cost and high in production efficiency. At the same time, they have the characteristics of high strength, good setting properties and good fluidity. They can replace traditional cement single-liquid grouting materials, effectively reduce the use of silicate cement and are conducive to the reuse of solid waste resources.

[0100] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other variations or modifications can be made based on the above description. It is impossible to exhaustively list all embodiments here. All obvious variations or modifications derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. A nickel-iron slag-based grouting material for the back wall of a shield tunnel, characterized in that: The composition by mass parts is as follows: 30-50 parts blast furnace nickel-iron slag, 20-50 parts fly ash, 5-20 parts boron mud, 0.5-3 parts activator, 5-20 parts blender, 80-110 parts activator solution, 100-150 parts recycled fine aggregate, 3-5 parts admixture, and the water-cement ratio of the nickel-iron slag-based shield tunnel wall backfill grouting material is 0.45-0.

8. The blast furnace nickel-iron slag is a solid waste slag produced during the smelting of nickel-iron alloys. Its chemical composition, by weight percentage, is as follows: SiO2: 25-30%, Al2O3: 25-35%, CaO: 20-30%, FeO: 3-5%, MgO: 5-10%. The blast furnace nickel-iron slag is ball-milled and activated using a planetary ball mill with an activator for 60-120 minutes at a speed of 350-450 rpm. The resulting blast furnace nickel-iron slag powder, obtained by passing through a 200-mesh sieve, has a median particle size of 6-10 μm and a specific surface area of ​​500-650 m². 2 / kg; The activator is desulfurized gypsum, and its chemical composition by weight percentage is as follows: CaO: 40~50%, SO3: 45~55%, SiO2: 3~5%, median particle size 3~5μm; The fly ash, by weight percentage, has the following chemical composition: SiO2: 55-65%, Al2O3: 15-22%, Fe2O3: 5.5-10%, CaO: 3.3-7%. It is a low-calcium fly ash with a fineness of over 200 mesh and a specific surface area of ​​600-700 m². 2 / kg; The boron mud has the following chemical composition by weight percentage: MgO: 45~55%, Al2O3: 2~5%, SiO2: 22~27%, CaO: 10~13%, Na2O: 1~3%, and passes through a 30-mesh sieve; The activator solution is prepared from water glass, solid sodium hydroxide particles, and added water. The mass ratio of solid sodium hydroxide particles to water glass is 0.1~0.

25. The water glass modulus M = the number of moles of SiO2 / the number of moles of Na2O is 3.3, and the Baumé degree is 38.

5. The water-cement ratio is the mass ratio of added water in the activator solution, water in the water glass, and solid cementing material. The solid cementing material is blast furnace nickel-iron slag, fly ash, and boron mud. The blending agent is coal gangue powder, and its chemical composition by weight percentage is as follows: SiO2: 52-65%, Al2O3: 16-36%, Fe2O3: 2-10%, CaO: 0.4-2.3%, MgO: 0.4-2.4%; The recycled fine aggregate is composed of waste concrete. After being crushed, the waste concrete is ball-milled mechanically for 30-180 minutes at a speed of 400-500 rpm. The fineness meets the following requirements: 10-0% residue on a square-hole sieve with a side length of 4.75mm, 45-25% residue on a 2.36mm sieve, and 65-45% residue on a 1.18mm sieve. The additive consists of 0.5-2 parts by weight of polycarboxylate superplasticizer, 0.5-2 parts by weight of hydroxypropyl methylcellulose ether, and 0.5-2 parts by weight of redispersible latex powder.

2. A method for preparing the nickel-iron slag-based shield tunnel wall grouting material as described in claim 1, characterized in that: Includes the following steps: 1) Weigh out 30-50 parts of blast furnace nickel-iron slag, 20-50 parts of fly ash, 5-20 parts of boron mud, 0.5-3 parts of activator, 5-20 parts of blender, 80-110 parts of activator solution, 100-150 parts of recycled fine aggregate, and 3-5 parts of admixture according to the following weight proportions. 2) Use a drying oven to dry the blast furnace nickel-iron slag and recycled fine aggregate until the moisture content is no more than 1%. Use a ball mill to mix the activator with the blast furnace nickel-iron slag, grind and sieve to obtain blast furnace nickel-iron slag powder; after crushing the recycled fine aggregate, it is ball-milled mechanically, and the ground recycled fine aggregate is sieved to obtain recycled fine aggregate sand as medium sand. 3) Add solid NaOH granules to the added water while stirring continuously to prevent NaOH from clumping, to obtain a NaOH solution; further mix and stir the water glass with the NaOH solution to obtain an activator solution; 4) Add blast furnace nickel-iron slag powder, fly ash, and boron mud to a planetary mixer and mix at a speed of 60-80 r / min for 80-100 s to obtain a mixed powder. Then add an activator solution in the same weight proportion and mix thoroughly at 60-80 r / min for 3-5 min to obtain a cementitious slurry. 5) Add recycled fine aggregate, modifier and admixture to the cementitious material slurry and stir at a speed of 120~250r / min for 1~3min to obtain nickel-iron slag-based shield tunnel wall backfill grouting material.

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